Self-propelled compaction rollers



Dec. 13, 1966 J. M. PARAMYTHIOTI 3,291,014

SELF-PROPELLED COMPACTION ROLLERS Filed March 30, 1,964 5 Sheets-Sheet 1 //v van 701? JEAN M/cwa AkAMYTH/DT/ Dec. 13, 1966 J. M. PARAMYTHIQTI 3,291,014

SELFPROPELLED COMPACTION ROLLERS Filed March 30, 1964 5 Sheets-Sheet 2 //VVE/V7'0/f JEAN MICHEL PARAMYfH/OT/ 5a x /w-akm d 2% Dec. 13, 1966 J. M. PARAMYTHIOTI 3,291,014

SELF'PROPELLED COMPACTION ROLLERS Filed March 50, 1964 5 Sheets-Sheet 3 FlGb ,100 5 75 03 FIG-8 A 105 104 1 7 L5. hwzwro es 752} Jan 44/0/51. X102 P/mAMyrH/or 66 w 76 Wm M HTTM nited States Patent 9 Claims. ici. 94-50 The present invention relates to compaction rollers and in particular to self-propelled compaction rollers having their wheels fitted with pneumatic tires. It is more particularly directed to machines of this kind adapted to work which necessitates the compaction of large volumes of soil, such as earth dams, airport landing strips and motorways.

It is well known to those skilled in the art that all other factors such as total weight, tire pressure, compaction speed, being equal, the cfficiency of a compaction roller expressed in cubic metres compacted per hour, is favourably aifected by the maximum concentration of the load per wheel obtained by either or a combination of the following means:

(a) Limitation of the number of wheels of the compactor to the minimum compatible with lateral and longitudinal stability of the machine;

(b) Arrangement of the wheels as close as possible to each other.

With regard to point (a) above, it is generally accepted that a very heavy compaction roller within the range of 50 to 200 tons should not be supported by more than four giant wheels mounted abreast in the centre of the roller on a single axle shaft.

While this method of grouping the wheels gives a correct lateral stability to the machine, this is not the case for the longitudinal stability, and this type of compactor is always hauled, the tractor coupling hook constituting the third point of support which is essential to longitudinal stability.

The concentration of loads in accordance with point (b) above can be obtained by means of a compaction roller with two rows of wheels mounted very close to each other, but in this case also, the essential longitudinal stability requires the co-operation of an external support, and in fact this type of compaction roller is also intended for coupling to a tractor.

If, on the other hand, the pneumatic-tired compactor must be self-propelled, its inherent stability must be independent of any external support and, up to the present time, it has been accepted, as in the case of the majority of wheeled automobile vehicles, that the compactor must be supported by wheels arranged in rows which are spaced as far as possible apart from each other.

Taking account of the fact that in the general case of all civil engineering equipment, and in particular in the case of compaction rollers, self-propelled machines are most appreciated because of their flexibility of use, the invention has for its object a self-propelled compaction roller with pneumatic tires which ensures a better concentration of the stresses applied by the Wheels and thus offering advantages as compared with equipment existing at the present time. It has therefore for its object the production of compaction rollers in which the axles of the rolling wheels, most of which are driving wheels, are very close together, which ensures the concentration of the stresses applied on the ground and therefore a very effective compacting action, and also ermits the production of machines which are very easy to handle.

A self-propelled compaction roller according to the invention, comprising a chassis which rests on the ground through a plurality of pneumatic-tired wheels, carried by 3,29lfil4 Patented Dec. 13, 1966 at least one transverse axle, part of the said wheels being driving wheels, is characterized in that all the wheels forming the main support are arranged vertically substantially below the centre of gravity of the chassis, each wheel being mounted at one extremity of an oscillating arm pivoted on the said chassis at the other extremity about a horizontal transverse axis, and a hydraulic jack, the oil supply circuit of which is coupled to a pneumatic pressure accumulator, being interposed between the chassis and a point on the oscillating arm distinct from the articulation point on the chassis, while the chassis additionally carries at each of its extremities a secondary supporting means, the said supporting means being disposed on the longitudinal axis of the chassis.

The secondary supporting means ensure especially the longitudinal stability and, when so desired, the lateral stability of the chassis and, relieving the rolling wheels from this function of stabilization, make it possible to mount the latter closer together and even to group them, when so required, on a single axle shaft.

The invention also provides for the constitution of these secondary supporting means by sliding surfaces, and to provide the compaction roller with means for modifying the ratio of the supported weights, carried on the one hand by the said sliding surfaces and on the other by the whole of the wheels forming the main support.

A further object of the invention is also to permit the production of a self-propelled compaction roller, in which the chassis is as low as possible with a view to obtaining great stability and also to facilitate the ballasting and unballasting of the said roller when so required.

A further object of the invention is also to permit the production of a self-propelled compaction roller, in which the close mounting of the wheels, especially in the case where these are arranged on a single axle shaft, facilitates the steering of the roller and enables very short-radius turning circles to be obtained by the simple known means consisting of braking the right-hand or left-hand wheels of the roller, or alternatively consisting of using a different speed for the right-hand wheel as compared with the left-hand wheel.

The characteristic features and advantages of the invention will furthermore become more clearly apparent from the description which follows below, given by way of example only, reference being made to the accompanying drawings, in which:

FIGS. 1 and 2 represent two views in elevation and in plan with cross-section, of one form of construction of a compaction roller according to the invention, in which the carrying wheels are grouped together on a single axle shaft;

FIG. 3 is a diagrammatic representation of the suspension circuit of the compaction roller shown in FIGS. 1 and 2;

FIG. 4 is an alternative form of the suspension circuit referred to above;

FIG. 5 is a diagrammatic representation of the control circuit of the driving wheels of the compaction roller shown in FIGS. 1 and 2;

FIGS. 6 and 7 illustrate two views in elevation and in plan with cross-section, of a further form of embodiment of the compaction roller according to the invention, in which the carrier wheels are grouped together on two axial shafts;

FIG. 8 is a diagrammatic representation of the suspension circuit of the roller shown in FIGS. 6 and 7.

A compaction roller according to the invention, in the form of embodiment shown in FIGS. 1 and 2, comprises a ballaste-d chassis 1 which rests on the ground through a series of carrier wheels 3 with pneumatic tires, grouped together on a transverse axle shaft 4. Each wheel shaft is for example mounted at one extremity of an arm 6 pivoted at its other extremity on the chassis, about a horizontal axis 7 by means of bearings S fixed to the said chassis; the various arms 6 can oscillate about each side of a horizontal position.

The roller further comprises two supporting means 10, each arranged at one extremity of the chassis, on each side of the wheels 3 in the longitudinal direction of the chassis, and each provided at their lower extremity with a sliding surface 11 intended to be in contact with the ground.

The body of the roller is an element of generally parallelpiped shape made up of welded sheet steel and divided into three compartments. The central compartment 13, open at the top and the bottom, contains the four wheels 3 and is flanked by the two compartments 15 and 16, the lower portion of which constitutes the secondary supported means 10.

This compartment 15 is partitioned internally and contains a heat engine 17 intended to drive two hydraulic pumps 18 and 19 having a variable output. The pump 18 supplies in parallel two hydraulic motors 20 and 21, each associated with one of the wheels of the right-hand pair of wheels, while the pump 19 supplies in parallel two hydraulic motors 22 and 23, each associated with one of the wheels of the left-hand pair of wheels. The supply circuit of these motors will be again referred to later.

The remainder of the free space of the compartment 15 and, at the other extremity, the compartment 16, are occupied by the fuel-oil and water tanks, the driving station 24 for the operator and the other essential equipments of the machine. The spaces 26 and 27 which still remain vacant at the extremities of the roller are intended to receive ballast.

Between the free extremity of each arm 6 and a pivotal point 28 fixed at the central part of the chassis, is arranged a hydraulic jack 29, the supply circuit of which communicates with one or a plurality of pressure accumulators, pneumatic for example, as will be described in more detail later. It is thus possible to act on the part of the load carried by a support by pumping oil into the jacks, or by letting oil escape from them, and in this way it is possible to regulate the distribution of the loads between the rolling surfaces, that is to say the wheels 3 and the sliding surfaces, namely the surfaces 11 in such manner especially as not to cause these to support anything but a very small proportion of the load of the machine, irrespective of the variations of weight of the machine or the nature of the ground.

There has been shown in FIG. 3 the diagram of a simple hydro-pneumatic circuit which permits this regulation of the distribution of loads between the wheels and the sliding surfaces.

This circuit comprises the four hydraulic jacks 29 each associated with a wheel 3. Each jack 29 comprises a cylinder 30 in which is slidably mounted a piston 31, the rod of which is pivoted on the arm 6 associated with the said Wheel. The four cylinders 30 are put into communication with each other by means of a conduit system 32 which terminates at an oleo-pneumatic accumulator 33 of a known type, from which leads a piping system 34 terminating at a hydraulic pump 35 through the intermediary of a control valve 36, the said pump being also associated with a safety valve 37 and with an oil tank 38 in the usual manner. The invention also provides the pressure accumulator with a control pressure gauge 39 which is mounted in a position where it can be seen by the operator.

The operation of the circuit is as follows: by actuating the control valve 36, the operator can either send oil into the hydraulic circuit 32, which increases the pressure in this circuit and in consequence the load on each wheel 3, or on the contrary, he can withdraw oil from this circuit and by this means can transfer a part of the load on the wheels to the sliding surfaces 11.

In this example, the four cylinders 30 of the jacks 29 being coupled to each other, the wheels 3, considered alone, are equivalent to a single supporting weight, which constitutes a hypostatic suspension; these wheels therefore do not contribute either to lateral stability or longitudinal stability of the machine. The stability of the machine in this case depends solely and exclusively on the fraction of the total weight of the roller which rests on the wide bases of the sliding surfaces 11.

It will furthermore be readily understood that this stability, and in particular the lateral stability which is the most threatened, will be progressively reduced as and when the weight is progressively transferred from the sliding surfaces to the wheels. In certain cases, it will in consequence be more advantageous to produce a suspension comprising two separate pressure circuits, as indicated in FIG. 4, one of the circuits being allocated to the two right-hand wheels and the other to the two left-hand wheels. It is then clear that the lateral stability is ensured in all cases, the two pairs of wheels contributing to it together, even if the sliding surfaces do not carry any weight or any load.

In the diagram of FIG. 4, the two cylinders 30 of the left-hand pair of wheels are coupled by a pipe 32 to a pressure accumulator 33 to which is connected as previously, through the intermediary of a pipe 34 and a control valve 36, a pump 35 associated with a tank 38 and with a safety valve 37. Identical elements designated by the same references being associated with the right-hand wheels of the compaction roller in a manner quite independent of those already referred to.

By reading the graduated pressure gauge 39 connected on the hydraulic circuit of the suspension, the operator can easily verify that the weight applied on the wheels is a substantial percentage of the total weight, for example the 10% remaining being carried by the sliding surfaces.

It may be noted that the type of hydraulic suspension described above ensures a practically equal distribution of the load between the four wheels. This fact has an importance which is Well known to technicians and has formed the subject of French Patent No. 1,052,794 filed on Jan. 12, 1952 by the present applicant.

FIG. 5 is a diagrammatic representation of the hydrostatic transmission which ensures the drive to the wheels.

As previously described, with each of the right-hand wheels there is associated a hydraulic motor 20 and 21 respectively, supplied in parallel through the piping systems 40 and 41 by a variable-delivery hydraulic pump 18 driven by a heat engine 17. This same engine 17 drives a variable-delivery hydraulic pump 19 which supplies in parallel through the piping systems 42 and 43, two hydraulic motors 22 and 23 each associated with the pair of left-hand wheels. Following a known technique, to improve the circulation of oil in the circuits and thus to prevent its heating, there can be provided an artificial leakage 46 connected by the conduits 47-48-49-50 and 51 to the hydraulic pumps and to the hydraulic motor, this leakage being added to the natural leakages of the hydraulic pumps and motors, and the compensation of these leakages being ensured by topping-up pumps 53 and 54, connected to the conduits 40-41-4243.

In the form of embodiment shown in FIG. 5, it is thus provided to drive independently the right-hand wheels and the left-hand wheels, if necessary at different speeds, or

even with different directions of rotation. This result is obtained by varying the flow-rate of oil from the pumps 18 and 19, which provides a means of steering the roller, this means being already known and utilized on other machines. It will be noted that the hydrostatic transmission thus utilized provides easy braking for the roller and also the reversal of its direction of running.

The same type of compaction roller could of course be also driven by means of another type of transmission, in

particular by a chain associated with each wheel and driven in turn by conventional means which will not be described in detail. By reason of the transmission from the heat engine to the driving wheels, it will be noted that the reaction of the driving torque of the wheels involves a modification of the distribution of the loads at rest, which fact is known to persons skilled in this particular art. Genenally speaking, for a displacement of the machine in a given direction, the load is transferred from the front sliding portion to the rear sliding portion and, under certain conditions comprising especially a high rate of load on the driving wheels and a high value of the torques applied to these wheels, the front sliding surface can be caused simply to graze the ground and even to lose all contact with it. In this case, the roller moves forward somewhat in the manner of an outboard motor-boat, the rear sliding portion being in firm contact with the soil while the front sliding portion is lifted-up, which facilitates the passage of the machine over obstacles on uneven ground.

There have been shown in FIGS. 1 and 2 elements 56 of the sliding surface. These elements have the shape of a spindle or a fish and are preferably made of abrasionresistant steel, for example of 14% manganese steel. They are arranged facing the spaces which separate the wheels and are adapted to produce a compacting and spreading action on the non-compacted material left between the tracks of the tires of the roller.

FIGS. 6 and 7 illustrate a further form of construction of the roller according to the invention, and relate to a self-propelled compaction roller in which the wheels are again grouped together in the central position of the roller, but are arranged on two 'aXle shafts 60 and 61 disposed symmetrically with respect to the vertical transverse plane passing through the centre of gravity of the chassis 1.

The said wheels are eight in number, grouped together in two rows of four on the \axle shafts 60 and 61. On the axle shaft 60 are mounted the four wheels 63 to 66, each mounted at one extremity of an oscillating arm 67 to 70 respectively articulated by its other extremity to the chassis 1 about a horizontal axis 71 close to the front extremity of the chassis. These wheels are spaced apart from each other by a distance substantially equal to the thickness of the pneumatic tires with which the said wheels are equipped.

The other four wheels 73 to 76 are mounted on the second axial shaft 61, each at the end of an oscillating shaft 77 to 80 articulated by its other extremity to the chassis about a horizontal axis 81 in the vicinity of the central region of the chassis. These last four wheels are mounted in staggered relation with respect to the wheels of the first row. The eight wheels are driving wheels. and with each of them there is associated a hydraulic motor (not shown), mounted in the interior of the wheel, at the extremity of the corresponding oscillating arm.

With each oscillating arm there is associated a hydraulic jack such as 87 for the arm 70 and 97 for the arm 80, arranged between the chassis 1 and the axle of the wheel associated with the corresponding oscillating arm. The two left-hand jacks of the row 60, corresponding to the wheels 65 and 66, and the two right-hand jacks of the row 61 corresponding to the wheels 75 and 76, are connected to each other by a conduit 98 to a hydraulic circuit comprising a source of oil under pressure, for example a pump controlled by a valve with four ways (not shown) and a pressure accumulator 99.

In the same way, the other four jacks corresponding on the one hand to the right-hand wheels 63 and 64 of the row 60 and, on the other hand, to the right-hand wheels 73 and 74 of the row 61 communicate with each other by means of a conduit 100 coupled to a hydraulic 6 circuit similar to that specified above, also comprising a source of pressure (not shown) and a pressure accumulator 101.

A valve 102 mounted on the conduit 98 enables the jacks corresponding to the wheels 75 and 76 to be isolated from the accumulator 99 or to be put into communication with this latter while a cock 103 enables the jacks corresponding to the wheels 73 and 74 to be isolated from the accumulator 101 or, on the contrary, to be put into communication with this accumulator. The jacks corresponding to the wheels of the axle shaft 61 are also connected to each other by a conduit 104 coupled by a conduit 105 to a third pressure accumulator 106. A cock 107 is arranged on this conduit 105 and the second cock 108 is mounted on the conduit 104, and enables the jacks of the pairs of right-hand and left-hand wheels of the axle shaft 61 to be coupled together or isolated (FIG. 8).

For compacting, the cocks 102, 103 and 108 being open and the cock 107 being closed, the eight cylinders of the jacks are coupled together, which enables the same load to be provided on all the wheels. On the other hand, by closing the cocks 102 and 103 and opening the cocks 107 and 108, it is possible to separate the front jacks from the rear jacks and to separate the front left-hand jacks from the front right-hand jacks, thereby constituting a vehicle with three points of support, constituted by the Wheels alone.

This arrangement can be employed for the transfer of the roller from one site to another, the chassis of the machine not being at all in contact with the ground. The longitudinal stability is then no longer ensured by the front and rear sliding surfaces. It will however be noted that even in this case, as the wheels are grouped together in the centre of the roller, the latter may show a tendency to pitching during its movement, and it will be desirable normally to provide auxiliary stabilizing means for the roller during such displacement.

What I claim is:

1. A self-propelled compaction roller comprising a chassis which rests on the ground through the medium of a plurality of wheels with pneumatic tires carried by at least one transverse axle, some of the said wheels being driving wheels, said plurality of wheels forming the main support for said chassis and being disposed substantially vertically in line with the centre of gravity of the chassis, each wheel being mounted at one extremity of an oscillating arm articulated on said chassis by its other extremity about a transverse horizontal axis, and a hydraulic jack having its oil supply circuit coupled to a pneumatic pressure accumulator mounted on said roller and being interposed between said chassis and a point on said oscillating arm distinct from said point of articulation on the chassis, said chassis being further provided at each of its extremities with a secondary supporting means, said supporting means being arranged on the longitudinal axis of said chassis.

2. A compaction roller as claimed in claim 1, in which the axes of the wheels of the main support are arranged on a single transverse axle shaft.

3. A compaction roller as claimed in claim 1, in which the axes of the wheels of the main support are arranged on two forwardly and rearwardly disposed transverse parallel axle shafts.

4. A compaction roller as claimed in claim 3, in which the wheels of each axle shaft are disposed in staggered relation with respect to the wheels of the other axle shaft.

5. A compaction roller as claimed in claim 1, in which the wheels of said main support form two groups arranged respectively on each side of the central longitudinal plane of the chassis, the hydraulic jacks corresponding to the wheels of each said group communicating with each other and being connected to a pressure accumulator associated with said groups.

6. A compaction roller as claimed in claim 5, and further comprising means for varying the pressure of said pressure accumulators.

7. A compaction roller as claimed in claim 1, in which said secondary supporting means are each constituted by a supporting surface adapted to slide on the ground and formed by the sole-plate of a shoe.

8. A compaction roller as claimed in claim 7, in which said sole-plate is provided with ribs parallel to the longitudinal axis of the chassis.

9. A compaction roller as claimed in claim 1, in which a hydraulic motor is associated with each driving wheel.

References Cited by the Examiner UNITED STATES PATENTS 2,029,659 2/1936 Greiner 94-50 2,270,390 1/ 1942 Summers 94-50 3,025,775 3/1962 Grace 9450 3,060,818 10/1962 Roberts 94-50 FOREIGN PATENTS 151,815 6/1953 Australia. 1,041,818 10/1953 France.

CHARLES E. OCONNELL, Primary Examiner.

N. C. BYERS, Assistant Examiner, 

1. A SELF-PROPELLED COMPACTION ROLLER COMPRISING A CHASSIS WHICH RESTS ON THE GROUND THROUGH THE MEDIUM OF A PLURALITY OF WHEELS WITH PNEUMATIC TIRES CARRIED BY AT LEAST ONE TRANSVERSE AXLE, SOME OF THE SAID WHEELS BEING DRIVING WHEELS, SAID PLURALITY OF WHEELS FORMING THE MAIN SUPPORT FOR SAID CHASSIS AND BEING DISPOSED SUBSTANTIALLY VERTICALLY IN LINE WITH THE CENTER OF GRAVITY OF THE CHASSIS, EACH WHEEL BEING MOUNTED AT ONE EXTREMITY OF AN OSCILLATING ARM ARTICULATED ON SAID CHASSIS BY ITS OTHER EXTREMITY ABOUT A TRANSVERSE HORIZONTAL AXIS, AND A HYDRAULIC JACK HAVING ITS OIL SUPPLY CIRCUIT COUPLED TO A PNEUMATIC PRESSURE ACCUMULATOR MOUNTED ON SAID ROLLER AND BEING INTERPOSED BETWEEN SAID CHASSIS AND A POINT ON SAID OSCILLATING ARM DISTINCT FROM SAID POINT OF ARTICULATION ON THE CHASSIS, SAID CHASSIS BEING FURTHER PROVIDED AT EACH OF ITS EXTREMITIES WITH A SECONDARY SUPPORTING MEANS, SAID SUPPORTING MEANS BEING ARRANGED ON THE LONGITUDINAL AXIS OF SAID CHASSIS. 